parse.y: Deprecate flip-flops

Ref #5400

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63667 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

parse.y

@@ -9809,8 +9809,10 @@ cond0(struct parser_params *p, NODE *node, int method_op, const YYLTYPE *loc)
       case NODE_DOT3:
 	node->nd_beg = range_op(p, node->nd_beg, loc);
 	node->nd_end = range_op(p, node->nd_end, loc);
-	if (nd_type(node) == NODE_DOT2) nd_set_type(node,NODE_FLIP2);
-	else if (nd_type(node) == NODE_DOT3) nd_set_type(node, NODE_FLIP3);
+	if (nd_type(node) == NODE_DOT2 || nd_type(node) == NODE_DOT3) {
+	    nd_set_type(node, nd_type(node) == NODE_DOT2 ? NODE_FLIP2 : NODE_FLIP3);
+	    parser_warn(p, node, "flip-flop is deprecated");
+	}
 	if (!method_op && !e_option_supplied(p)) {
 	    int b = literal_node(node->nd_beg);
 	    int e = literal_node(node->nd_end);

test/ruby/test_syntax.rb

@@ -940,7 +940,9 @@ eom
       eval('1 if !//')
     end
     assert_warn('') do
+      verbose_bak, $VERBOSE = $VERBOSE, nil
       eval('1 if !(true..false)')
+      $VERBOSE = verbose_bak
     end
     assert_warning('') do
       eval('1 if !1')